Differential driving mechanism.



A. P. BRUSH. DIFERENUAL www@ MECHMMSM.

MPUCATIGN FILED SAN. 13, 1ML

ALANSON P. BRUSH, 0F DETROIT, MICHIGATG DIFFERENTIAL DRIVING MECHANISM.

lpeoicat on of Letters Patent.

Patented Nov. 19, 1918.

Application filed January 18, 1917. Serial No. 142,128.

To all 'whom it may concern Be it known that l, ALANsoN P. BRUSH, acitizen of the lnited States. residn at Detroit. in the county of Ylayneand tate of Michigan, have. invented a certain nen4 and usefulImprovement in Differential Driving Mechanism, of which the following isa full, clear, and exact deseril'ition.

The ordinary differential driving incolla-l nism in common use on motorears hns desir able qualities and capacities which overlm; ance itsdeficiencies. or otherwise it noni) not be in general use. lt is,however. wel: understood that it is defective, in that. uw der eel-taincircumstances, the turnintof the differential gear may result in turningone only of the two associated driven shafts. Such conditions may arisewhen one of the driving wheels is on a slippery surface on which it hasno traction. In that event the turning of the differential gear willresult in the turning of this particular wheelwithout turning the otherwheel at all, although that other wheel may vhave sullicient traction todrive the car if it could be made to turn.

The object of this invention is io relieve the ordinary differentialmechanism of the above noted defect., without in any material degreeinterfering with the performance of its usual beneficial functions. Tothis end the invention consists in the construction and combination ofparts shown in the drawing and hereinafter described and pointed outdefinitely in the appended claims.

In the drawings, nal central section differential driving mechanismpresent invention applied thereto.

Referring to the parts by reference charactors, 10 and 12 represent twoalined driven shafts which are interconnected through differentialgearing, of which 15 represents the rotatable differential drum, whlchis rotatably mounted to rotate about an axis which is coincident to theaxis of the two alined shafts 10 and 12. In the specific constructionshown this differential drum is formed with two oppositely extendedelongated hubs 16 and 17 which are rotatably mounted in suitableanti-friction bearings upon the casing member 20. The two shafts 10 and12 are independently rotatable within the hubs 16 and 17 respectively;and the beveled ears 13 and 14 which respectively have rivingconnections with the two shafts 10 Figure 1 is a longitudi of a commonforni of with the and l2, are in mesh with the compensating pinions 18rotatably mounted upon the differential drum. A. ring gear 19 is fixedto this dili'erential drum whereby the drum may be turned by the drivingshaft 22 and the beveled gear 23 thereon. To the extent described thisdifferential driving mechanism is of familial' well understood construction. Those familiar with this art will likewise understand thatpower will be transmitted respectively from the shafts 10 and l2 to thetwo driving wheels of the car through suitable mechanism, of whichseveral varieties are in common use.

25 and 26 are two torsion coil springs which respeetii'elv surround theshafts 10 and l). The spring 25 is connected at one end to the shaft 10and at its other end with the hub 16 of the differential drum,-while theother springr 26 is connected at one end with the shaft 12 and at itsother end with the hub 16 of the differential drum. These springs,therefore, form elastic connections between the, differential gearingand the two shafts respectively'. Under normal conditions, that is tosav, when the car is travelinglr in a straight path, the turningr of'the differential gearing will cause both of the shafts 10 and 12 toturn in the same direction and at the same speed as is the usual case.When the ear is turning a corner the springs do not have anv sucheffect; upon the two shafts l0. 12. as will prevent their rate ot'rotation from becoming automatically differentiated to t e extentnecessary. In other words, in the ordinarv functionin of thedifferential mechanism` the descrlbed springs 25, 26, perform nofunction. If, however, for any reason, one wheel ofl the shafts 10, 12,is driven faster than the other,- and this may happen under theconditions hereinbefore mentioned, namely` when one wheel is on aslipperv surface where it has no traction while the other wheel is on asurface where it has adequate traction, the two springs will be putunder tension, and when the limit of that tension is reached theindependent rotation of the two shafts is no longer possible. From thattime on both shafts must rotate in substantial imison with each otherand the differential gear. In any event, both shafts must be turned inthe same direction in which the differential gear is being turned. It isapparent that as the springs are twisted as above described they willhave a disposition bo shorten; and in.

the construction shown they are permitted to shorten bv reason of thefact that cach spring* is at one end made fast to a sleeve 27 which hasa tone-ne and groove connection with thc associated slit/itt, such thatcompels the slome to turn with the shalt but permits the slet-,ve tomore lengthwise npon the shaft :1 short, distance.

After the construction described has iunctioncd in the manner aboveexplained, the two springs will ot course be left, in :in undesirablecondition; but thev will antoniaticallv vtend to resume their nornnilconditions, and will in fact do thiswithin a short time, because during;anv continuons driving in a straight line or substantially straight linethere will be intermittent contact oi' the driving wheels with the roadsui-tace, that is to say, the wheels will lic continuait)r bounding!`nti" 'of' the road sin-tace: and when over the wheels leave the roadsurface the associated springs will be 'permitted to and will moretoward their normal positions. This action will he repented with more orless rapidity, :ind lil-fore n great while the springs will havereturned to their normal positions and conditions. and the device willbe again in position to verfornii its ordinari' functions in theordinarv wav without any substantial interference or modification by thesprinns.

It will be understood that the omission of one of the springs Q5. 2thwill not prevent the mechanism from acting in substantially thedescribed maniiei.` because in that event thc shafty with which thespringr connected will when that spring' has been pnt under .sufficienttension be compclledto rotate with this differential gear; wherefore thecompensating gears can not turn on their axes and therefore thi` othershaft must rotate with the dii'ercntial near.

Having described niv claim:

1. In driving mechanism. the combination of two alined driven shafts.diii'erential invention, l

mechanism therebetween comprising a differential drum, coiniiensatinnfgears mounted thereon, and ,scars respcctivelv connected with said twoshafts and engaging said compensating nears. and mechanism connectingsaid dill't-rcntial drinn and one ot said shafts mechanism therebetween,and an elastic c0nuection between one of sind shafts and sandVdiiferential mechanism.

3. In driving mechanism` the combination of two alined driven shafts.differential mechanism therebetween. a torsion coiled spring whichembraces one of the shafts and connected at one end to the differentialmechanism and at its other end With said shaft.

si.. In drivingV mechanism. the combination of two alincd driven shafts.diierential mechanism therebetween. a. torsion coiled sprin' whichsurrounds the shaft and is'connecten at one end with the differentialmechanism, and a sleeve having` a sliding drivinf.;l connection withsaid shaft with which the other end of said spring is connected.

5. In driving.r mechanism` the combination of two alined driven shafts.differential mechanism therebetween. and two torsion coiled springswhich respectively surround said shafts cach beiner connected at one endwith the differential mechanism and at the other end with the associatedshaft.

In testimonv whereof. I hereunto allix mi signature in the presence oftwo Witnesses.

ALANSON P. BRUSH.

viitnesses i OWEN M. NAcKElL Tnnouomi W. MARSH.

